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Engineering in Medicine and Biology Magazine, IEEE

Issue 2 • Date March-April 1997

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Displaying Results 1 - 13 of 13
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  • Cantilevers and tips for atomic force microscopy

    Page(s): 28 - 33
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    The key component of the atomic force microscope (AFM) is a cantilever with a tip. The tip must be sharp enough to record with high lateral resolution the topography. The cantilever must also have the appropriate compliance and resonant frequency for the type of operation selected, which can be either a contact or a noncontact mode of operation. The requirement for a low spring constant (less than 1 N/m) and a high resonant frequency (greater than 10 kHz) led to silicon micromachining techniques early on in the development of the AFM. Silicon micromachining is a technology by which a silicon wafer is processed through a series of deposition, photolithography, and etching steps to produce a mechanical structure with dimensional tolerances in the order of 1 μm. The use of silicon micromachining techniques has benefited the AFM in several aspects: (1) sharper tips can be manufactured with micromachining techniques than with alternative electrochemical etching techniques, as used for scanning tunneling microscopy tips; (2) batch fabrication simultaneously of thousands of cantilevers guarantees a high degree of reproducibility in the mechanical properties of the cantilevers; and (3) micromachined cantilevers are inexpensive. View full abstract»

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  • Observing interactions between the IgG antigen and anti-IgG antibody with AFM

    Page(s): 42 - 46
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    Spatially specific interactions between the immunoglobulin G (IgG) antigen and anti-IgG monoclonal antibody (McAb) have been studied in detail by tapping-mode AFM. The binding numbers and binding sites of the antigen molecules with antibody molecules, as well as the conformational changes during the binding process have been revealed. The wider application of this technique to complex systems has considerable potential for study of a variety of antigen-antibody interactions and may be extended to other bio-macromolecular systems. View full abstract»

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  • Force-distance curves by AFM

    Page(s): 58 - 65
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    Since 1989, the atomic force microscope (AFM) has emerged as a useful tool in studying surface interactions by means of force-distance curves, and a great deal of work has been carried out on both its theoretical and experimental issues. AFM is able to acquire force-distance curves from every kind of surface, with high lateral (1 Å), vertical (0.1 Å) and force (1 pN) resolution. Moreover, the study of force-distance curves provides a deeper knowledge of the physics of contact, and hence of all the phenomena connected with AFM imaging techniques. In this article, we review force-distance curve theory, and show through curves acquired with a home-made microscope the main surface interactions that can be revealed. View full abstract»

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  • Producing prefabricated tissues and organs via tissue engineering

    Page(s): 73 - 80
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    Loss and failure of organs and tissues are obviously major health-care problems. Living-organ and tissue transplantation have been the easiest solutions to these problems so far, but having enough donor material for all patients is unrealistic. Tissue engineering is an emerging area in biomedicine that may help solve this problem. Methods involved in tissue reconstruction include using cells alone or the association of cells with tridimensional scaffolds for more complex tissues, while organ reconstruction requires cells, scaffolds, homing systems and integration with mechanical systems and microelectronic devices. Here, the authors review the state of the art in tissue engineering and also touch upon organ engineering. View full abstract»

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  • Building knowledge-based systems with an assembling technique

    Page(s): 81 - 83
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    In the field of medical knowledge engineering, it is a common expectation that the number of diseases contained within a given system should constantly increase. The authors' effort to develop an enormous knowledge-based system (the Enormous Electronic-Brain Erudite, EBME) has extended for more than 10 years. The reason for such a long time-frame is that EBME has a huge knowledge base that consists of 1,001 diagnostic entities. It is not only time consuming and tedious but also very error-prone to build this type of database manually. To overcome this problem of time and accuracy, we put forward an assembly technique for knowledge-based systems, which we describe in this article. Our research direction is to develop a methodology to build an enormous knowledge-based system. The goals of this study are: (1) to enhance the efficiency of knowledge engineering by automating the knowledge engineering processes (2) to avoid repeated labor as much as possible (3) in an enormous knowledge-based system, to assemble different subsystems that not only meet the different needs of different users, but also are useful to avoid the occurrence of "combination explosion" (4) to advance the research of medical information processing standardization. View full abstract»

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  • Organ transplants

    Page(s): 84 - 86
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    Not long ago organ transplants were headline news about frontier medicine; now they are commonplace. Today both the number of transplants and long-term survival are increasing. In addition, physicians have learned how to keep increasingly sick patients alive longer and how to make more people eligible for transplants. The dark cloud in this sunny picture is the shortage of donated organs. According to the United Network for Organ Sharing (UNOS), which coordinates transplant registration, 3448 people died in 1995 because organs were not available for them in time. Last summer there were about 47,000 Americans awaiting transplants, but if this year is similar to 1995, only about 40% of them will actually receive an organ. A third to a half of all people on waiting lists die before an organ can be found for them. This shortage raises several difficult ethical problems, which can only be outlined in the space available here. Topics discussed include: i) how should the limited supply of organs be distributed? ii) should donors be encouraged to donate by the use of financial incentives? iii) the definition of death; iv) animal donors; v) organs from healthy donors; and vi) the changing physician-patient relationship. View full abstract»

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  • Sequencing Support System: A robotic system for processing DNA samples

    Page(s): 92 - 93
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    The development of very high-throughput and autonomous robotic workstations will be necessary to quickly and efficiently complete the sequencing of the 3 billion nucleotide base pairs that make up the human genome. The key to our sequencing scale-up efforts is the development of the Sequencing Support System. The Sequencing Support System is an integrated robotic workstation built around a 3-meter rail robot. The Sequencing Support System is currently assembling cycle sequence reactions and thermal cycling and consolidating reactions. We are currently testing plaque picking and DNA purification methods that can be effectively and quickly integrated with our current platform. Our intent is to quickly develop and construct an autonomous high-throughput system that is replicatable for inclusive large-scale sequencing efforts. This integrated workstation will consist of the Sequencing Support System; a bank of automated sequencers; and a custom 192-channel oligo synthesizer, a vital instrument critical to labor intensive "finishing" efforts (sequencing methods directed at filling gaps and improving the quality of the produced DNA sequence). Each of these components are now operational as separate modules. Data transfer and assembly are automated in software on Mac and Sun computers. Our next system, currently in the planning phase, will be solely dedicated to automated high-throughput "finishing". The system will comprise the Sequencing Support System's components and will include a Beekman Biomek workstation specifically tasked to manipulate individual clones. View full abstract»

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  • A biosensor based an micromechanical interrogation of living cells

    Page(s): 66 - 72
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    The authors have demonstrated that living cells can be reliably cultured directly onto atomic force microscope (AFM) cantilevers. The cells are inclined to grow on both sides of the surface, and the cantilevers must be treated to deter such two-sided growth. Preliminary data acquired with the AFM demonstrate that these integrated cell/cantilevers are capable of detecting the response of Madine Darby canine kidney (MDCK) cells to different toxins, with response time on the order of several seconds. These results suggest the feasibility of real-time, rapid, and sensitive biomechanical sensors. A separate fluid chamber has been built, which is capable of detecting fluid temperature changes of tenths of a degree. The initial temperature results from the fluid chamber prototype indicate the potential for a low-cost dedicated system View full abstract»

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  • Atomic force microscopy: a new way to look at chromatin

    Page(s): 34 - 41
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    This article deals with the application of a new form of microscopy, atomic force microscopy or AFM, to the study of chromatin structure. The main advantage of AFM is that it can operate at subnanometer resolution in aqueous fluids. It has been applied successfully to study of the structural dynamics of cells and molecules. However, thus far most of the AFM work on chromatin has been limited to studies performed in ambient air environments. Even when working in ambient air, AFM offers a number of important advantages over other microscopic techniques: (1) sample preparation is simple, e.g., no stains or metal coatings need to be applied to the specimen; (2) without coatings or stains present, AFM measurements can be made directly on the natural surface of the specimen; (3) imaging can be performed in humid environments where biological specimens remain hydrated with bound water molecules; and (4) the spatial resolution of AFM is sufficient to allow clear visualization of individual nucleosomes and linker DNA View full abstract»

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  • The software license with teeth

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    What happens when a graduate student in computer science buys a telephone directory on CD-ROM and uses the directory to start a business on the Internet? Can he take advantage of the legal rule that the content of telephone directories is not protected by copyright law, or is he bound by the license that came with the box of software. Those were the questions before the court in the recent case of ProCD Inc. vs. Zeidenberg. ProCD brought suit in Wisconsin federal court for infringement of its copyrights and for breach of the shrink-wrap license. On its copyright claim, ProCD ran headlong into a 1991 Supreme Court case-the Feist case-which held that the contents of telephone directories are not protected by the copyright laws because they lack sufficient creativity. Based on this case, the district court found that Zeidenberg had done nothing wrong under the copyright laws in using ProCD's directory. ProCD did no better on its shrink-wrap license claim. With its business in jeopardy, ProCD had no choice but to appeal the district court's decision to the Seventh Circuit Court of Appeals. This time ProCD won. The appeals court focused its attention on the shrink-wrap license. On the question of whether the license was a binding contract, the court noted that many commercial transactions involve paying first and receiving contract terms later. Of critical importance to the court was the fact that ProCD's license agreement allowed the purchaser to return the product after reading the license. Accordingly, although Zeidenberg did not have an opportunity to negotiate the terms of the license, if he did not agree to them, he could have sent the product back. ProCD's victory represents an important breakthrough in computer law since it is the first appellate case to enforce a shrink-wrap license. Future cases are likely to refine this decision, but for now, shrink-wrap licenses clearly have more teeth than ever before View full abstract»

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  • Measuring the elastic properties of biological samples with the AFM

    Page(s): 47 - 57
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    We discuss AFM applications in measuring or applying small forces. Instrumentation is reviewed, as well as the ability of the AFM to image living cells and measure elastic properties of biological material and cells on the submicrometer scale. AFM resolution as it pertains to soft materials is also discussed View full abstract»

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  • Heritage of the tissue-bed oximeter

    Page(s): 87 - 91
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    The pulse oximeter is well established in clinical medicine as a monitor of the efficacy of the cardiorespiratory system. The principle of this device represents the end of a long evolutionary line of noninvasive instruments designed to measure the redness of blood i.e. oxygen saturation. This historical note describes the many ingenious devices that are the heritage of the pulse oximeter, which was described by Nakajima et al. (1979) and Yoshiya et al. (1980) View full abstract»

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Aims & Scope

IEEE Engineering in Medicine and Biology Magazine contains articles on current technologies and methods used in biomedical and clinical engineering.

 

This Magazine ceased publication in 2010. The current retitled publication is IEEE Pulse.

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